The geomagnetic field was quiet on August 26. The high latitude magnetometer at Andenes recorded quiet to active conditions. The August 23 CME was observed arriving at DSCOVR at 00:24 UT on August 27 when there was a sudden increase in both solar wind density. Only weak geomagnetic effects have been recorded so far.
Solar flux density measured at 20h UT on 2.8 GHz was 88.6 - increasing 13.1 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 77.89). The Potsdam WDC planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 4.6). Three hour interval K indices: 22121011 (planetary), 22232302 (Boulder), 32122243 (Andenes).
The background x-ray flux is at the class B2 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 6 active regions using 2K resolution (SN: 144) and in 5 active regions using 1K resolution (SN: 93) SDO/HMI images.
Region 12859 [N18E08] developed as new flux
emerged. The region produced a C3 flare at 18:18 UT which triggered a
filament eruption. An EIT wave covering a large part of the visible disk was
observed afterwards. A faint full halo CME could be seen in LASCO imagery.
Further C class flares are possible.
Region 12860 [S29E29] developed significantly with increasing
polarity intermixing. M class flaring is possible.
New region 12861 [N15E52] emerged on August 25 and was numbered by
SWPC the next day as slow development continued.
Spotted regions not observed (or interpreted
differently) by SWPC:
New region S7050 [N19E31] was observed with
tiny spots in an old plage area.
New region S7051 [S28W52] emerged with several spots.
New region S7052 [S18E49] emerged with tiny spots.
C2+ flares:
| Magnitude | Peak time (UT) | Location | AR | Recorded by | Comment |
| C3.0/1F | 18:18 | N20E14 | 12859 | GOES16 | full halo CME |
| C3.9 | 23:22 | S32E23 | 12860 | GOES16 | LASCO imagery not yet available |
August 24: A slow moving CME was observed mainly over the east limb
following a filament eruption just after noon. Some material was observed
off the west limb as well, however, it is uncertain if this was associated
with the same event.
August 25: No obviously Earth directed CMEs
were observed in available LASCO imagery.
August 26: A faint full halo CME was observed after the C3 flare and
associated erupting filament. The CME could arrive on August 29.
[Coronal hole history (since October 2002)]
[Compare today's report to the situation one solar rotation ago:
28 days ago
27 days ago
26 days ago]
A small northern hemisphere coronal hole (CH1027) was Earth facing on August 23.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle and high latitudes is poor. Propagation on long distance northeast-southwest paths is poor to fair.
The geomagnetic field is expected to be quiet to unsettled on August 27 due to effects from CH1027 and the August 23 CME. There is a slight chance the August 24 CME could have an Earth directed component, if so that disturbance could arrive late on August 27 or on August 28. The August 26 CME could arrive on August 29 and cause unsettled and active intervals.
| Coronal holes (1) | Coronal mass ejection (2) | M and X class flares (3) |
1) Effects from a coronal hole
could reach Earth within the next 5 days. When the high speed
stream has arrived the color changes to green.
2) Effects from a CME are likely to be observed at Earth within 96 hours.
3) There is a possibility of either M or X class flares within the next 48 hours.
Green: 0-30% probability, Yellow: 30-70% probability, Red: 70-100% probability.
(Click on image for 2K resolution).
4K resolution.
Compare to the previous day's image. 0.5K image
When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue is positive.
Data for all officially numbered solar regions according to the Solar Region Summary provided by NOAA/SWPC, all other regions are numbered sequentially as they emerge using the STAR spot number. Comments are my own, as is the STAR spot count (spots observed at or inside a few hours before midnight) and data for regions not numbered by SWPC or where SWPC has observed no spots. SWPC active region numbers in the table below and in the active region map above are the historic SWPC/USAF numbers. SWPC data considered to be not sufficiently precise (location, area, classification) are red colored.
| Active region | SWPC date numbered STAR detected |
Spot count | Location at midnight | Area | Classification | SDO / HMI 4K continuum image with magnetic polarity overlays |
Comment | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| SWPC/ USAF |
Magnetic (SDO) |
SWPC | STAR | Current | Previous | ||||||
| 2K | 1K | ||||||||||
| S7040 | 2021.08.18 | S25W18 | |||||||||
| S7041 | 2021.08.20 | N28W39 | |||||||||
| 12859 | 2021.08.20 2021.08.21 |
4 | 21 | 9 | N16E06 | 0050 | DSO | DSO |
 |
 |
location: N18E08 area: 0090 |
| S7044 | 2021.08.23 | N31W14 | |||||||||
| 12860 | 2021.08.24 2021.08.24 |
12 | 47 | 25 | S30E14 | 0150 | DAO | DAI |
 |
 |
location: S28E15 area: 0350 beta-gamma |
| S7048 | 2021.08.24 | N23E06 | |||||||||
| 12861 | 2021.08.25 2021.08.26 |
1 | 5 | 2 | N15E53 | 0010 | BXO | CRO |
 |
 |
|
| S7050 | 2021.08.26 | 2 | 1 | N19E31 | 0006 | BXO |
 |
||||
| S7051 | 2021.08.26 | 7 | 6 | S28W52 | 0025 | CRO |
 |
||||
| S7052 | 2021.08.26 | 2 | S18E49 | 0002 | AXX |
 |
|||||
| Total spot count: | 17 | 84 | 43 | ||||||||
| Sunspot number: | 47 | 144 | 93 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 27 | 100 | 59 | (Sum of total spot count + classification weighting for each AR. Classification weighting: X=0, R=3, A/S=5, H/K=10) | |||||||
| Relative sunspot number (Wolf number): | 52 | 79 | 74 | ||||||||
| Month | Average solar flux | International sunspot number (WDC-SILSO) |
Smoothed sunspot number (4) | Average ap (3) |
|
|---|---|---|---|---|---|
| Measured | 1 AU | ||||
| 2014.02 | 170.3 (cycle peak) |
166.3 | 146.1 (cycle peak) | 110.5 | 10.70 |
| 2014.04 | 143.9 | 144.8 | 112.5 | 116.4 (solar max) | 7.88 |
| 2017.09 | 91.3 | 92.3 | 43.6 | 18.2 (-1.3) | 18.22 (cycle peak) |
| 2019.11 | 70.2 | 68.7 | 0.5 | 2.0 (-0.6) (Solar minimum using 365d smoothing: November 17, 2019) |
4.19 |
| 2019.12 | 70.8 | 68.6 | 1.6 | 1.8 (-0.2) (ISN 13 months smoothed solar minimum) |
3.22 |
| 2020.02 | 71.0 | 69.3 | 0.4 | 2.7 (+0.5) | 6.16 |
| 2020.03 | 70.2 | 69.5 | 1.5 | 3.0 (+0.3) | 5.63 |
| 2020.04 | 69.5 | 70.0 | 5.4 | 3.6 (+0.6) | 5.32 |
| 2020.05 | 69.0 | 70.6 | 0.2 | 5.6 (+2.0) | 3.80 |
| 2020.06 | 69.5 | 71.7 | 5.8 | 7.9 (+2.3) | 3.75 |
| 2020.07 | 69.5 | 71.8 | 6.3 | 9.0 (+1.1) | 4.28 |
| 2020.08 | 71.6 | 73.4 | 7.6 | 9.5 (+0.5) | 5.68 |
| 2020.09 | 70.7 | 71.4 | 0.7 | 10.5 (+1.0) | 8.59 |
| 2020.10 | 74.6 | 74.2 | 14.6 | 11.9 (+1.4) | 6.13 |
| 2020.11 | 89.9 | 88.0 | 34.5 | 13.6 (+1.7) | 4.77 |
| 2020.12 | 86.9 | 84.2 | 23.1 | 15.3 (+1.7) | 4.72 |
| 2021.01 | 76.0 | 73.6 | 10.4 | 17.3 (+2.0) | 4.39 |
| 2021.02 | 74.3 | 72.4 | 8.3 | (19.8 projected, +2.5) | 9.50 |
| 2021.03 | 76.0 | 75.2 | 17.3 | (23.2 projected, +3.4) | 10.17 |
| 2021.04 | 75.9 | 76.4 | 24.5 | (27.3 projected, +4.1) | 8.40 |
| 2021.05 | 75.3 | 77.1 | 21.2 | (30.0 projected, +2.7) | 6.50 |
| 2021.06 | 79.4 | 81.8 | 25.3 | (33.2 projected, +3.2) | 5.52 |
| 2021.07 | 81.0 | 83.6 | 34.4 | (37.8 projected, +4.6) | 5.51 |
| 2021.08 | 75.1 (1) | 12.1 (2A) / 15.0 (2B) / 20.5 (2C) | (42.5 projected, +4.7) | (5.3) | |
| 2021.09 | (48.2 projected, +5.7) | ||||
| 2021.10 | (52.6 projected, +4.4) | ||||
| 2021.11 | (57.2 projected, +4.6) | ||||
| 2021.12 | (63.0 projected, +5.8) | ||||
| 2022.01 | (66.6 projected, +3.6) | ||||
1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz
and any corrections applied to that measurement.
2A) Current impact on the monthly sunspot number based on the Boulder (NOAA/SWPC) sunspot number (accumulated daily sunspots / month days).
2B) Boulder SN current month average to date.
2C) STAR SDO 1K Wolf number 30 day average.
3) Running average based on the quicklook and definitive Potsdam WDC ap indices. Values in red
are based on the definitive international
GFZ Potsdam WDC ap indices.
4) Source: SIDC-SILSO.
This report has been prepared by Jan Alvestad. It is based on the analysis of data from whatever sources are available at the time the report is prepared. All time references are to Universal Time. Comments and suggestions are always welcome.
SDO images are courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.
